Registering clinical thermometer.



No. 641,080. Patented Ian. 9, I900. L. F. COMITTI.

REGISTERING CLINICAL THERM UMETER.

(Application filed Aug. 1 1 1899.)

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LUIGI FEDELE OOMITTI,

OF LONDON, ENGLAND.

REGISTERING CLINICAL THERMOMETER.

SPECIFICATION forming part of Letters Patent No. 641,080, dated January 9, 1900. Application filed August 11,1899. Serial No. 726,896. (No model.)

To a whom it may concern.-

Beit known that I, LUIGI FEDELE COMITTI, a subject of the Queen of Great Britain, residing at 69 Mount Pleasant, London, England, have invented certain new and useful Improvements in Clinical and other Registering Thermometers, (for which application has been made in Great Britain, No. 700, dated January 11, 1899,) of which the following is a specification.

This invention relates to maximumtemperature-registerin g thermometers; and it has for its object to provide a thermometer of the character described wherein the severance of the mercury after having indicated the temperature is greatly facilitated.

To this end my invention consists in the features and in the construction, arrangement, and combination of parts hereinafter described,and particularly pointed out in the claim following the description.

In registering-thermometers of the type referred to, as generally constructed, there is a small portionof mercury contained in a bore of very fine diameter in the thermometertube, which is separated from the column of mercury after it has risen to the maximum point and as it again falls, the point where the division takes place being a constriction of the bore, which constriction by relieving the column of mercury above of so much of its weight stays or retards its fall, and the mercury below the constriction, being unsupported, returns to the bulb or reservoir. This remaining portion of the column constitutes the index and indicates the maximum degree attained.

Various constructions have been proposed for facilitating the severance of the column of mercury and for increasing the sensitiveness of this class of instruments and the delicacy of the indications. In one plan of construction ashort length of index mercury in a fine bore is separated from the main column by an air speck or bubble, and the air-speck when the mercury rises is carried up, and on the recession of the mercury below the airspeck the mercury above said air-speck is left at the highest point and there registers the maximum temperature. When the thermometer is again required for use, this small portion of mercury is caused to descend by swinging or otherwise bringing centrifugal force to bear on the mercury to make it return to the ordinary enlarged part of the bore near the bulb. The inconvenience attending this and similar constructions is the liability of not only forcing the index portion of the mercury back to the desired position in the enlarged part of the tube, but to also force it into the bulb itself, and the air-speck thereby becomes lost and the thermometer ceases to register. Another method has been devised whereby the air-speck is trapped at an enlargement of the bore at a determined point, whereby the mercury of the index is caused to assume a globular form, with the consequent disinclination to further pass down the bore to the bulb below. According to another method the bore of the tube is contracted to a knife-edge at a determined point at a distance of from half an inch to an inch from the neck of the bulb, whereby the column of mercury having by expansion risen to its maximum height in cooling contracts and withdraws into the bulb, the column being separated at the knife-edge which offers greater resistance to the return of the index portion of the column. When the index portion is desired to be lowered, this is effected by a peculiar swinging or jerking action which is well understood. Movable parts have also been employed in the bore in the nature of valves to permit the rise and prevent the fall of the mercury Without the aid of. swinging to overcome such detaining means. Again, it has been proposed to overcome some of the difficulties and inconveniences attendant upon the manufacture and use of such thermometers by placing] the knifeedge contraction for producing the index in close proximity to the bulb. I am also aware that it has been proposed to provide a plurality of contractions in the bore of the thermometer, so as to enable the contractions to be less acute and to facilitate the passage of the mercury therepast when the instrument is swungfor resetting. According to another proposed construction the index-bore of very fine dimensions at a point below the graduated indicating portion of the tube becomes somewhat suddenly merged into one of larger diameter or into a larger cavity or cavities between the bulb and such indicattoo ing-tube, so that the enlarged bore or cavity may contain a comparatively considerable weight of mercury with a contraction or constriction in this enlarged bore to restrain the return of the mercury to the index-bulb during contraction. Again, it has been proposed to furtherimprove such thermometers by providing a mercurychamber consisting of a swelling or enlargement of the ordinary bore at a point above the constriction or contraction referred to, so as to facilitate the use of the modern constructions using a small bulb and very fine bore, with the attendant advantage of quickly registering the temperature, owing to the utilization of the capillary attraction of the fine bore for the mercurial column, the alleged effect of this device being thaton shaking the thermometer to reset the same for use the body of mercury in said chamber will act to force some of the mercury down through the contraction and at the same time draw some of the mercury in the bore down into the chamber and enabling the thermometer to be reset with very little effort and leaving its sensitiveness and accuracy unimpaired.

According to the present invention, a very fine indicating-tube of the thermometer is made as usual, and the contraction is provided in the ordinary manner at a suitable distance below in order to restrain the return of the index column of mercury to the bulb and to cause the separation of such column from the main body of mercury to form an indestructible index. I form, however, below and in close proximity to the said constriction or contraction in the bore a chamber or enlargement of the mercury, and when contraction of the latter occurs the mercury in said chamber instead of remaining lodged therein passes wholly or mainly down the bore to the bulb. In shaking or swinging the thermometer to reset it for further use this chamber greatly facilitates the return of the mercury of the index portion by the enlarged outlet provided and serves as a receptacle for the mercury to lodge in-that is to say, by making the parts so that the body of mercury may be so much larger near the contraction it is possible to make the contraction much larger without impairing the function or operation of the contraction, and thus facilitate resetting while preserving the registering function of the thermometer.

Referring to the drawing, wherein is illustrated a view in elevation of my improved thermometer, the numeral 1 indicates the glass thermometer-tube; 2, the bore therein, and 3 the constriction or contracted portion of the bore constructed in the usual manner. A chamber or enlargement 4 is formed in the bore below and in close proximity to said constriction or contraction for'lodgment of mercury, said chamber connecting by a contracted part 2 of the bore with the usual bulb, so that when contraction of the mercury occurs the mercury in said chamber instead of being held therein passes either wholly or partially down the contracted part 2 of the bore to the main body of mercury in the usual bulb 5. In shaking or swinging the thermometer to reset the mercury the said chamber greatly facilitates the return of the index portion of the mercury by the enlarged outlet provided and serves as a receptacle for the mercury to lodge in.

The numeral 6 indicates the fine graduated index constructed as usual for indicating the height of the index portion of the mercury.

Having thus described my invention, what I claim is A maximum temperature-registering thermometer comprising a thermometer-tube provided with a fine index and having a bore formed with a constriction or contracted portion at a point below the index, and an enlargement formed in the bore beneath the constriction or contraction and in proximity thereto and connected by a contracted part of the bore with the bulb, substantially as described and for the purposes specified.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

LUIGI FEDELE OOMITTI. Witnesses:

ALFRED GEORGE BROOKES, ERNEST JOHN HILL. 

